Decorative lighting devices, for providing ornamental luminous displays, are increasing in popularity. One known example of a decorative lighting device makes use of a so-called ‘conical deglaring plate’ which comprises a light transmissive array of cone-shaped structures, distributed on a supporting substrate. When spots of light are directed onto a surface of the deglaring plate, the spots are each transformed by the structure of the plate into a corresponding circular shaped light pattern visible on a reverse side of the plate.
Known devices incorporating such plates typically utilise them to provide attractive luminous displays of circles and other closed curved forms. In some cases, the structure of the plate is configured such that an apparent brightness or shape of the circular patterns appears to change as a user moves their position relative to the visible surface of the plate.
WO 2015/095189 A1 for example discloses a number of different prismatic deglaring plates, each comprising an array of micro-prism structures adapted to generate visible light patterns for an observer. Each plate is formed by adapting the micro-prism shape, pitch and/or arrangement to generate different effects, which includes light patterns which appear to change in dependence upon user position (e.g. changing brightness, or sparkle effects).
However, it remains a challenge, using such arrangements, to generate light outputs whose patterns are sufficiently interesting to capture and hold the attention of observers. In particular, observers may quickly grow uninterested or bored of the patterns produced by the device, so that creating a display which can remain fully captivating to onlookers for an extended period of time is far from straightforward.
There is a need therefore for conical deglaring plate based lighting devices capable of producing more interesting or captivating luminous displays.